Anyone ever go faster after switching from 1.6 intake rockers to 1.5? I’m thinking velocity increase with less lift. Which is better, velocity or volume on intake flow?

More lift sometimes makes more power and sometimes it doesn't. Just depends what the engine needs.
https://www.motortrend.com/how-to/trying-find-extra-power-rocker-arm-testing/

Waht andy said, and I would add that you need to make sure you are still controlling the valve, if you add lift with a higher rocker ratio and lose control of the valve you will probably lose power.

If your talking SB I would always run the highest rocker ratio I can find to bring the pushrod up straighter (I know it's not much but it don't hurt) then match my cam to those rockers to get the valve action I want.

Read something awhile back, I think it was Joe Mondelo. You want no more lift than 15% of your bore diameter. My 511 has a bore of 4.375 and my lift with a 1.65 rocker puts it over 15% of the bore. My measured lift is .665 . The 15% rule would be .656. The optimal target is 12%, but not over 15%. I’m thinking with my victor head(which I think suffers from lack of enough velocity) may benefit with a 1.55 rocker instead. A 1.55 gives me .625 measured lift. Just a thought.

Personally I feel that you will see more of a change with changes to the valve timing events, rather than just lift itself. Using rocker arm ratio as an example, is the increase or decrease in lift making the power? Or is it the change of valve timing events and valve velocity showing the increase/decrease in power?

Billy Godbold has talked about a multiplication factor he uses for calculating valve lift.

He works on 0.45 - 0.48 of the intake valve. As an example 2.25" intake valve x 0.45 = 1.0125" of valve lift. On a Super Stock or Pro Stock style engine it sounds about right. You're probably not going to apply that factor to some of the engines we build.

The only way you'll know is test it

There are various formulas to get you in the ball park but you have to understand the assumptions used to create the formula before you know if you should use it or not. PipeMax will tell you how much lift you need for a certain combination to avoid choke. I always run the engines thru PipeMax before ordering parts. It is just a quick and easy way to double check my assumptions.

I give up

Thanks Andy. Appreciated the linc as well.

I agree and that is gonna happen first. I only mentioned the rocker ratios because of my victor max wedge heads. Most that have used them found them to be underperforming(RAMM). Dwayne told me they have a very large bowl on the intake, almost as big as the valve. I believe that huge bowl may be the reason. It could be causing the air to slow at the bowl allowing fuel to drop out of suspension. My thought was maybe a short ratio rocker arm would help keep the air/velocity thru the bowl with the shorter lift. Besides, I may have to switch from 1.65 to 1.55 to get more piston to valve cleanse anyway. I’m just try to get the p/v clearance without killing any power. A new cam on a 110 is my last resort.

There is a lot of info on this page I just came across. cylinderhead flow tech book

...and that theory was based on what?

So here is what I'm thinking:

1) assuming that a wedge head is used, and therefore for a particular valve diameter size increasing the lift brings the valve closer to the cylinder wall, therefore shrouding the valve

2) but #1 above is certainly going to be impacted by the valve angle in the head (which is why I said "wedge" b/c a hemi chamber would certainly not follow these rules quite as readily I'm thinking)

Not saying this theory has no merit to it, but I'd like to understand what criteria it is based on.

Anything more than 15% of the bore diameter in valve lift and turbulence is created off the back of the valve, which kills the velocity. With a 1.65 rocker I’m over 15%, plus I have a [censored] designed head. Thought it might be a win win for me. Plus I might gain a bit of p/v clearance too. So a win win win actually.

Never mind

I'm sure thats the whole deal. That valve too close to the cylinder wall will kill it. I think i will plan for the 1.55 rockers in place of the 1.65.

I've never reduced rocker ratio and gone faster, but I've added rocker ratio without seeing any gains.

[Have a nice day

Your right, I was thinking that wrong. The writer wrote that more than 15% of bore in lift created turbulence, killing velocity. I don’t know his theory.

That doesn't make any sense so I'd avoid following that theory. Race engines almost always have valve lift that is greater than 15% of the bore size. A 4.50 inch bore would be restricted to 0.680 lift which isn't enough for a big race engine. A big bracket engine will use lift somewhere in the 0.750 to 0.850 while a pro built engine will be up to an inch of lift.

That’s why I’m asking. Thought I would see if anyone else agrees with this.

I give up